Human Waste Fertilizers Stage a Comeback Amid Climate Pressures

Human waste is making a comeback as fertiliser in several countries. Sweden, Finland, Uganda, and pilot projects in Germany and the US now use processed urine or faeces to grow crops. The approach isn't new—ancient Rome and China once relied on it—but modern farming has long favoured synthetic alternatives. The shift comes as researchers highlight the potential of human waste to replace chemical fertilisers. Urine, when processed, provides a rich source of nitrogen, while composted faeces supply phosphorus and potassium. Studies suggest that nutrients recovered from wastewater could meet 15% to 50% of agriculture's phosphorus needs—a critical resource the EU classifies as finite.

Yet challenges remain. Modern sewage systems dilute waste, making large-scale collection difficult. The biggest hurdle, however, may be public perception. Despite its benefits, many people still recoil at the idea of using human excrement on fields. The EU currently bans the practice over hygiene concerns, though some nations, like Sweden, have used urine-diversion systems since the 1990s. The environmental stakes are high. Producing synthetic nitrogen fertiliser consumes vast amounts of energy and releases significant CO₂. Meanwhile, human waste contains around 40 million tons of nitrogen yearly—enough to cover roughly 20% of global demand. Pilot projects, such as those by US-based Rich Earth and Haiti's SOIL, demonstrate that safe, effective recycling is possible.

As phosphate reserves dwindle and climate pressures grow, interest in waste-based fertiliser is rising. Countries testing the method report promising results, though regulatory and cultural barriers persist. For now, the practice remains limited—but its potential to cut emissions and conserve resources keeps it firmly on the agenda.